How do pornstars make it through those brutal gangbangs shoots?

Lately I saw a gang bang movie of Sasha Grey. It was like some 20 guys breaking all hell loose upon her stuffing her everywhere with no mercy.I don't think any scene has been altered or something.She was pounded for several minutes by all of them and most of the time it was her butt hole that was targeted.Pain and anguish was clearly seen on her face and tears were tickling down her cheeks.

What I mean to ask is, isn't that a sort of abuse in disguise that girls undergo in the porn Industry ? Even the most experienced woman I have been with , didn't like me to get to harsh with that anal thing, then how could a girl like Sasha do it with several men? Does that mean female porn stars are some kinda super human, or are they helpless before the customer demands and sometimes push their limits putting their life and health on line? Have heard about some girls getting hospitalized after shoot.

No woman in her real sense would like to expose herself to that kinda danger situation no matter how kinky she is and whatever fetish she has.
If girls like Sasha and others do those brutal gang bang scenes for the fans, then hats off to them.I wish the industry get a bit safer for them when it comes to those extreme scenes.